high CVSS 7.8

CVE-2021-47046·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: drm/amd/display: Fix off by one in hdmi_14_process_transaction() The hdcp_i2c_offsets[] array did not have an entry for HDCP_MESSAGE_ID_WRITE_CONTENT_STREAM_TYPE so it led to an off by one read overflow. I added an entry and copied the 0x0 value for the offset from similar code in drivers/gpu/drm/amd/display/modules/hdcp/hdcp_ddc.c. I also declared several of these arrays as having HDCP_MESSAGE_ID_MAX entries. This doesn't change the code, but it's just a belt and suspenders approach to try future proof the code.

Severity
high
Software
Kernel
Fixed in
5.12.4
Published
2024-02-28

Affected versions

From: 5.12

Until: 5.12.4

Fixed in: 5.12.4

How to fix this CVE

Update your Linux kernel to version 5.12.4 or later to fix an array bounds vulnerability in the AMD display HDCP driver. This off-by-one error in hdmi_14_process_transaction() could allow local attackers with low privileges to read kernel memory or cause system instability. Apply the kernel update through your distribution's package manager immediately.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Step 1: Check your current kernel version with `uname -r` and compare it against the affected range 5.12 to 5.12.3
  2. Step 2: Verify AMD GPU/display driver is loaded using `lsmod | grep amdgpu` or `lsmod | grep drm`
  3. Step 3: Search kernel logs for HDCP transaction errors with `dmesg | grep -i hdcp` or `journalctl -b | grep -i hdcp`
  4. Step 4: After updating, run `uname -r` again and confirm the kernel version is 5.12.4 or higher

FAQ

What is CVE-2021-47046?

This vulnerability is an array bounds reading error in the AMD display driver's HDCP message handling code, where an uninitialized array index could lead to out-of-bounds memory access on systems with affected kernel versions.

Is CVE-2021-47046 being actively exploited?

No, this vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog and no public exploits are available as of the latest advisory data.

What versions of Kernel are affected by CVE-2021-47046?

Linux kernel versions from 5.12 through 5.12.3 are affected; kernel 5.12.4 and later versions contain the fix.

How do I check if my server is vulnerable to CVE-2021-47046?

Run `uname -r` to get your kernel version. If it shows 5.12.0, 5.12.1, 5.12.2, or 5.12.3, your system is vulnerable. You can also check `cat /proc/version` for detailed kernel build information.

Does Defensia detect CVE-2021-47046?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If the Linux kernel is installed on a monitored server running affected versions, CVE-2021-47046 will appear in your dashboard with remediation steps.

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References

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